Exposure meter



Nov. 7, 1950 A. T. WILLIAMS EI'AL EXPOSURE METER 3 Sheets-Sheet 1 Filed Oct. 29, 1946 gvwmm I Q 1950 A. T. WILLIAMS EI'AL 2,528,716

EXPOSURE METER Filed Oct. 29, 1946 s Sheets-Sheet 2 I ooooooo 711950 A. T. WILLIAMS ETAL 2,523,716

' EXPOSURE METER s Sheets-Sheet 5 Filed Oct. 29. .1946

Patented Nov. 7, 1950 EXPOSURE METER Alexander T. Williams, Westileld, and Paul Huber, Hillside, N. J., assignors to Weston Electrical Instrument Corporation, Newark, N. J., a corporation of New Jersey Application October 29, 1946, Serial No. 706,346

7 Claims.

This invention relates to photometers and to exposure meters such as are used to determine exposure data for photographic purposes.

The invention is not restricted to photometers of the photoelectric type but the particular embodiment which will be described is a photoelectric exposure meter of the double range type such as is described and claimed in Patent No. 2,274,- 441, Alexander T. Williams.

Objects of the invention are to simplify the mechanical construction of photometers and exposure meters, and to reduce the weight and the overall dimensions of such devices. to provide exposure meters with casings, having window openings at opposite faces for admitting light to a photocell and for viewing an instrument scale, and in which the casing includes an intermediate section of skeleton f orm upon which all elements of the photoelectric and measuring system are mounted, and, closures secured to the Objects are opposite faces of. the intermediate sectionfltd complete the casing. 5 v

These and other objects andiadvantages ofthe invention will be-apparent from the'iollowing descriptionwhentaken with: the accompanying drawings in which:

Fig. 1 is avfront elevation, with parts broken away, of an exposure meter embodying the invention; 1

Fig. 2 is a longitudinal section on line 2-2 of Fig.1;

Fig. 3 is an end elevation, with parts in section as seen on the plane of section line 3-3 or Fig. 1;

Fig. 4 .is a side elevation, withparts-insection as seen on the plane of lineJH ofFig'. 1;

Fig. 5 is a rear elevation'of the exposure meter;

Fig. dis-an end elevatiomwith partsin' section as seen on the planeo'f section line 6 6 of Fig. 1; and

Figs1-7'and 8 are fragmentary schematic front elevation and sideviews of the movable graduated scaleplateand associated parts.

In the drawings, the reference numeral I identlfles the intermediate section of the exposure meter casing, which section is a molded body of insulating material constituting an elongated base of skeleton form upon which the photocell 2 and all elements of the associated measuring instrument are mounted. A main or permanently operative light-restricting system comprising a multiple lens plate 3 and multiple compartment baflie 4 extends over the photocell 2, and an auxiliary bailie or relatively thick plate 5 having small diameter openings 6 in axial allnement with the lens elements, when the auxiliary bailie is in operative position, is hinged upon the base section I for movement into and out of operative position. A spring-pressed plunger 1 is slidably mounted on the baflle plate 5 to engagera'recess in the base section i to latch the auxiliary baille in operative position, the plunger having a knob 8 for latching the auxiliary baille in inoperative position.

The measuring instrument includes a coil 9 which is pivotally supported for angular move-- ment in the interpolar gap of a permanent magnet I 0, and'a pointer ll carried by thecoil for movement over a double range scale plate system. The coil 9 is preferablysupported by internal bearings such as described and claimed in the co-pending application of Paul Huber and Alexander T. Williams, Serial No. 706,376 filed October 29, 1946, which matured into Patent No. 2,463,770 on March 8, 1949.

.The high and low graduations l2, l3 of brightness; values are printed or engraved upon a plate I 4 which is supported for sliding movement between a back plate 15 and a scale plate [6 having a rectangular window I1 through which the scale graduations of the sliding plate It may be viewed. A scale [8 or series of lines extending radially of the axis of the moving coil 9 are drawn or etched on the scale plate [6 adjacent the window opening H.

The sliding plate It is guided for rectilinear movement by two screws l9 which are threaded into the base section i and support the inner end of the scale plate l6, and a stud 20 which is riveted to the back plate IS. The plate 14 is resiliently pressed upwardly (as viewed in Fig. 1) towards its low scale position, by a pair of hairpin springs 2| which are located adjacent the opposite edges of the base section I, each spring 2| having one end extending through an aperture in the sliding plate It and another end anchored to the base section I by a screw 22. The plate is moved downwardly, as viewed in Figs. 1, 7 and 8, to expose the high range graduations I! at the window opening I! of plate it when the auxiliary baille 5 is moved into operative position overlying the lens plate 3 to reduce the acceptance angle of the photocell. This shifting of the plate I4 is effected by a yoke 23 of generally U-form having ends slidably mounted in the base i and having notches in which the respective springs 2! are seated, the legs of the yoke being located in the path of movement of the inner-end of the auxiliary baflle i when it is adjusted into position over the lens plate 3. s

A domed cover plate 24 is secured to the base section i by screws 25 which extend through the base section from its rear face, and the plate 24 has an opening across which a window glass 26 is securedby means, not shown, to permit a view of the scale plates I4 and ii. A multiple disk computer 21 is mounted upon the cover plate 24, and the intermediate disk 28 thereof which is adjustable angularly in accordance with the film speed has a series of concealed openings 29 for cooperation with a locking pin 30 which extends through and is anchored in a keyhole slot of a link or strap 3i which is carried by a pushbutton 32. The pin 30 is normally projected into one of the openings 29 by a spring 33 which is seated in alined recesses in the basei and the pushbutton 32, and the pin is withdrawn to persign'and construction of photometers fall within the spirit of the invention as set forth in the following claims.

We claim l. A photometer comprising a'skeleton base section of insulating material having openings extending therethrough from one face to the opposite face thereof, a photocell and means mounting the same in one opening of the base section, a measuring instrument and means mounting the same in another opening of said base section, and apertured cover plates of opaque material secured over and substantially coextensive with said opposite faces of said base section to complete a casing for the photometer.

2. A photometer as recited in'claim 1 wherein one cover plate has a transparent plate over an aperture thereof for viewing the instrument and an aperture of the other cover plate admits light ,to the photocell.

3. A photometer comprising an elongated base section of insulating material having flat edge base section, screws extending through said base mit adjustment of the computer disk 28 by de- I pressing the pushbutton 32.

A gasket 34 is located in a recess extending around the flat edge of the base I, and the rim of the cover plate 24 seats upon the flat edge and engages the gasket to provide av tight joint for 4 .the casing. A second concave or domed casin cover 35 has a flat rim for seating upon the flat edgeportion at the other face of the base section I, i. e., the face at the right as shown in Fig.

2, and the rear face of the exposure meter when These openings in the front cover plate 35 are sealed by gaskets 31, 38 respectively. A zero corrector 39 is carried by the plate 35 and has an eccentric pin 40 extending through a slot in the angularly'adjustable abutment 4| to which the outer end of the spring- 42 of the coil 9 is anchored.

The rear cover plate 35 is secured to the base section I by a pair of pins 43 which are seated in alined and angularly arranged sockets at one end of the base section i and the coverplate 35, and screws 44 which may be threaded into the other end of the base section I or, as shown, into the counterbored and threaded ends of screws 25 which secure the other cover plate 24 to the base section. The heads of the screws 44 are preferably countersunk in the cover plate 3-"), and a name plate, is secured to the cover plate 35 by screws 41 toconceal the screws 44 which must be removed to gain access to the interior of the exposure meter casing. The name plate 46 is apertured to clear the latching opening 36 of cover plate 35 and the zero adjuster 39.

The cover plates 24 and 35 may be molded from limited -to the particular embodiment herein shown and described. and'that various changes which may occur to those familiar with the do section and into said 'cover plate to secure the same to the base section, a second domed cover plate having a rim seated upon the flat edge portion at the opposite face of said base section, each cover plate being substantially coextensive Y with and completely overlying said base section,

and means including screws extending through said second cover plate from the exterior thereof to secure the second cover plate to the base section to complete the casing of the photometer.

4. A photometer as recited in claim 3, wherein said securing means includes a pin extending into complementary sockets at one end of said elongatad base section and said second cover plate, the axis of the pin being inclined to the plane of the flat edge portion contacted by the rim of the second cover plate, the screws of said securing means being located adjacent the opposite end of said base section and the second cover plate.

5. A photometer as recitedin claim 3, in combination with a name plate detachably secured to said second cover plate to conceal the heads of the screws of said securing means.

6. A photometer as recited in claim 3, wherein said securing means includes a pin extending into complementary sockets at one end of said elongated base section and said second cover plate, the axis of the pin being inclined to the plane of the flat edge portion contacted by the rim of the second cover plate, the screws of said securing means being located adjacent the opposite end of said base section and the second cover plate, in

combination with a name plate detachably secured to said second cover plate to conceal the heads of the screws of said securing means.

' 7. An exposure meter comprising an insulating base section of elongated skeleton form, a photocell and a measuring instrument mounted on said base section, the measuring instrument including a pointer and cooperating scale means at the face of the base section opposite that upon which the photocell is mounted, a main baflle in fixed position overlying said photocell, an auxiliary batile pivotally supported upon said base section for angular movement into and out of an operative position overlying said main 'bai'ile, a front cover plate secured tosaid base section and having a window for viewing said pointer and scale ALEXANDER T. WILLIAMS. PAUL HUBER.

REFERENCES CITED The following references are of record in the file of this patent:

Number 6 UNITED STATES PATENTS Name Date Goldschmid July 26, 1892 Simpson et a1. Dec. 7, 1937 Mihalyi et al. Jan. 11, 1938 Weston July 12, 193 Bernhard et a1 Mar. 7. 1939 Devaux et a1. Mar. 28, 1939 Norwood Sept. 10, 12340 Williams Feb. 24, 1942 Whittenton Apr. 11, 1944 Reinarth July 11, 1944 Lamb Nov. 28, 1944 Wood June 4, 1946 Miller Oct. 8, 1946 

